Mechanical Pump Pressure Drop at WOT?

[carnutjw]

Would this cure your hose woes for the top of the tank? 24in/hg vacuum rated, 50 psi pressure

https://www.oreillyauto.com/detail/c/barricade/gates-barricade-fuel-hose/gaty/27315?q=3%2F8+hose&pos=7

Could you have inadvertently kinked the 3/8" hard line during installation?

 

[78Delta88]

I remember from before and you found the pump for the 454. Could be just weak pump or partial blockage. I seriously doubt it has anything to do with the pump rod or eccentric.

 

[bracketchev1221]

I don't know how accurate that calculator is. I can tell you for a fact a 1000 hp race engine is not getting by on a 75 GPH pump like that calculator says. There is acceleration forces pushing the gas back to the tank that the pump has to overcome. I would think there is a correction factor that yes maybe on a stand at rpm it may use less fuel but in a car I think it needs a lot more. Overall, dropping 6 to 4 psi at wide open throttle is not terrible but it showing the system is limited. My dad used to cross the finish line at 3 psi with his race car back in the 80's. He claimed as long as it had pressure there was gas in the bowl.

 

[86 Salon]

While there may be an issue with the fuel pressure dropping at higher speeds, if it's enough to keep the float bowl full, it probably will not cause any issues. I would still check all hoses and clamps for any damage because you may have issues down the road. If it was fuel injected, low fuel pressure would be a problem.

 

[78Delta88]

Another good reason for an A/F meter. If at WOT the meter shows going lean, going out of normal limits, that's bad. Going too lean at WOT is a nice precursor to engine damage.

Going somewhat lean at cruise helps increase MPG. Lean at wide open is bad, not good.

If your FP reduces to 4 psi, but not going lean, then it's something to improve on but not stress over. If it's going lean then the obvious is to resolve it as soon as you can.

 

[Supercharged111]

I did zap in a bung a year ago for just that purpose, and I may well be to the point of tuning with a wideband now that it's not just running out of fuel.